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Installing a Z10000-U Buffer Amplifier in a Yaesu
This page describes installing a Z10000-U broadband buffer amplifier in a Yaesu FT-1000MP
transceiver owned by Mike, W4XN.
The purpose of the Z10000-U buffer amplifier is to provide an isolated sample of the FT1000MP's 70.455 MHz first IF, ahead of the transceiver's roofing filter, so that it might be used
in conjunction with a panadapter.
I've provided these notes based on W4XN's installation. However, I assume no liability for any
damage you may cause to your transceiver should you follow these notes.
Z10000-U Buffer Amplifier
I built the Z10000-U buffer amplifier for 6.7 dB nominal gain. It is a standard Z10000-U amplifier.
Connection Point
At 70 MHz, the Z10000-U's
input impedance is
dominated by capacitance
on the input coaxial cable, if
any, and the PCB and
AD8007 IC's input
capacitance. The Z10000U's input impedance, with
zero input cable, at 70 MHz
is about 350 ohms, as
illustrated in the SPICE
input impedance simulation
shown below. My
measurements show the
SPICE simulation is
acceptably close to the
measured impedance.
FT-1000MP Transceiver
Installing a Z10000-U Buffer Amplifier in a Yeasu FT-1000MP Transceiver - Page 1 of 4 - DX Engineering, 2017
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There's no good IF pick-off point. The FT-1000MP's mixer (four FETs shown visible at the left
of the schematic fragment below) feeds T1016's primary winding. This is a balanced mixer (note
that T1016's primary is balanced with a center tap) so introducing a load onto one side of the
mixer is not a good idea.
T1016's secondary and T1017 form a coupled resonator filter and impedance matching
arrangement for XF1001, the first 70.455 MHz monolithic crystal roofing filter.
The selected signal pick-up point, T1016's secondary winding, is the best point available. It
turns out that T1016 and T1017 are at the back edge of the RF PCB, so it's possible to make
this connection with a very short length of coaxial cable to the Z10000-U's input.
Obtaining Access to the RF PCB
To obtain access to the RF PCB, it is necessary to remove the FT-1000MP's top and bottom
covers.
Then, remove the mounting screws for the blower assembly and the RF Power Amplifier
Output module. It is possible to carefully move these modules out of the way without removing
any of their wires.
Then remove the mounting screws securing the shield and RF Input PCB. In addition, the rear
of the PCB is attached to the FT-1000MP's rear panel via two screws in the remote band
selection DIN connector. Remove the two screws that go into the DIN connector.
There are two connectors on the left rear edge of the PCB that must be removed before the
Installing a Z10000-U Buffer Amplifier in a Yeasu FT-1000MP Transceiver - Page 2 of 4 - DX Engineering, 2017
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board can be tilted up for work. One is a ribbon cable. Slide the connector locking mechanism
up and gently remove the ribbon cable. The ribbon cable does not have separate pins, but
rather the cable conductors are the mating surface. The second connector is a small
conventional wired connector adjacent to the ribbon connector.
With these two cables disconnected, it is possible to carefully lift and rotate the PCB to obtain
access to the bottom of the board.
The board has a number of PCB-mount RCA connectors as well. When removing the board,
slide it away from the rear panel to clear the connectors.
In addition to the RF and ground pickup, it is necessary to obtain +12V for the Z10000-U buffer
amplifier. This may be accomplished by connecting to the auxiliary +12V output fuse, located
on the RF Input board. Connect to the fuse output, not the input, of course.
The RF connection should be made with a very short length of coaxial cable, about 3/4 inch
long, or 20 mm for metric readers. The connection is made from the bottom of the PCB.
Angle the Z10000-U at right angles to the RF Input board, as illustrated in the photo below.
Adding the Z10000-U will detune T1016 and T1017 and it is necessary to re-peak both after
remounting the RF Input board. It is critical that the cable connecting the Z10000-U to the RF
Input board be kept very short, as even an extra half-inch of coaxial cable beyond the
recommended 0.75 inch may add so much extra capacitance that these two transformers
cannot be brought back into resonance.
To peak the transformers, apply a signal generator to the FT1000-MP's input, tune the receiver
to the signal generator input frequency in either CW or SSB mode. Watching the S-meter,
adjust T1016 and T1017 slugs for maximum signal strength.
Installing a Z10000-U Buffer Amplifier in a Yeasu FT-1000MP Transceiver - Page 3 of 4 - DX Engineering, 2017
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The image shows the
Z10000-U buffer
amplifier in place,
along with the RF Input
board.
We wound up attaching the Z10000-U board to the FT-1000MP's power supply board with tape.
This avoids drilling additional holes.
This installation used the optional SMA female bulkhead connector. We added a 0.25" (6.3 mm)
diameter hole to the FT-1000MP's rear panel near the remote band DIN connector. In making
the hole, several points should be observed:
1. The back panel's top rail is easily bent, as the heat sink ventilation holes reduce its strength.
Be careful not to bend the rear panel when working on it.
2. The RF Power Amplifier module takes up most of the vertical space above the RF Input PCB
and limits the output connector hole placement.
3. The usual precautions in making a hole apply. We used a Roper-Whitney XX hand
punch, rather than an electric drill. The punch leaves a clean hole without a burr and is much
safer as it can't get out of control and damage other parts of the transceiver like an electric drill
can.
Installing a Z10000-U Buffer Amplifier in a Yeasu FT-1000MP Transceiver - Page 4 of 4 - DX Engineering, 2017
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